This invention relates to an improved intravascular catheter and methods for use thereof.
Intravascular catheterization apparatuses have proven to be useful and efficient for both therapeutic and diagnostic purposes. Intravascular catheterization therapies, such as angioplasty, atherectomy, and laser irradiation, have been developed as alternatives to bypass surgery for treating vascular diseases or other conditions that occlude or reduce the lumen size of portions of a patient's vascular system. In particular, balloon angioplasty has proven to be a useful, and in many circumstances a preferred, treatment for obstructive coronary diseases. Also, intravascular diagnostic catheter apparatuses, for anglographics, ultrasonic imaging, and Doppler blood flow measurements for example, have been developed to measure or image the extent of an occlusion of a vessel, (e.g., stenosis).
These intravascular therapeutic and diagnostic catheter apparatuses have achieved acceptance because of their effectiveness as well as the fact that they can be used through a minor surgical procedure that is relatively non-disruptive to the patient compared to coronary surgery. These intravascular therapeutic and diagnostic apparatuses rely on the positioning of a catheter device into the vascular system of a patient via an incision at an accessible location which may be remote from the site of the occlusion or stenosis. For example, the accessible location may be the femoral artery at the groin. The intravascular device is then advanced through the incision via the femoral artery to the desired coronary distal site.
It is conventional in performing an intravascular coronary angioplasty procedure to use a guide catheter to support the balloon dilation catheter in the artery from the incision site to close to the coronary site. The guide catheter extends from outside the body to the ostium of the coronary vessel and provides a pathway via a lumen therein for the positioning of other intravascular apparatuses, such as the guide wire and the balloon catheter, through the artery to the coronary vessels. At the proximal end of the guide catheter there is a fitting, such as a luer lock, to which a manifold device such as a Y-adapter is connected. The dilation catheter is positioned through one of the ports of the Y-adapter (e.g. the axially oriented port) and into the guide catheter. This port of the Y-adapter through which the dilation catheter extends includes a hemostatic seal valve. The hemostatic seal valve includes a threaded knob that can be tightened down onto an O-ring seal located in a seat of the Y-adapter port. The hemostatic seal valve allows a physician to close the port when a dilation catheter is not in the guide catheter, or to seal the O-ring around the dilation catheter when it is in the guide catheter. Because the guide catheter provides a direct access to the artery, the hemostatic valve reduces or prevents bleeding from the artery both when a dilation catheter is in the artery and when a dilation catheter is not in the artery. Thus, the hemostatic seal valve located in a port of the Y-adapter facilitates intravascular procedures, such as angioplasty.
A difficulty sometimes encountered in the use of the hemostatic seal valve, as described, relates to adjusting the hemostatic valve to allow advancement of a balloon catheter while minimizing bleeding back through the valve. This difficulty is especially encountered when using a dilation catheter having a small diameter shaft. Catheters of this type include some fixed-wire type catheters and catheters having an opening to a proximal end of a guide wire lumen located in a distal portion of the shaft. A fixed-wire type catheter includes a non-removable wire tip located on the distal end of the dilation catheter. This wire tip is used for positioning the fixed-wire dilation catheter into the desired arterial site after it is advanced past the distal end of the guide catheter. The wire tip may be bent or formed with a J-configuration to facilitate steering it --and thus the dilation catheter-- into the desired location.
The dilation catheter is handled and steered from the proximal end. During this steering and positioning, the physician attempts to adjust the hemostatic seal valve so that it is loose enough to allow unimpeded advancement and steering of the dilation catheter from the proximal end for the delicate positioning procedure. If the hemostatic valve is clamped down too tight on the dilation catheter, it can cause considerable friction with the catheter shaft that can impede advancing and steering of the dilation catheter. On the other hand, if the hemostatic valve is too loose, it allows bleeding back through the guide catheter and out the Y-adapter hemostatic valve which is undesirable and which can also impede handling of the equipment. Thus, the physician is presented with an unsatisfactory trade-off between minimizing blood loss and maximizing unimpeded catheter shaft movement. Moreover, adjustment the hemostatic valve to provide an tolerable balance of these considerations can be difficult or tedious and time-consuming during an interventional procedure. Therefore, there is a need for a improvement that facilitates intravascular procedures and facilitates advancement and steering of an intravascular catheter, such as balloon catheter, through a hemostatic valve of a Y-adapter while at the same time minimizing or reducing bleeding back through the guide catheter around the hemostatic valve.